An abbreviation of grandmother; also the name of an idiot, famous for licking her eye, who died Nov. 14, 1719. Go teach your granny to suck eggs; said to such as would instruct any one in a matter he knows better than themselves.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Grannum’s Gold * Grapple the RailsNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes